JPS59225366A - Disconnection position detecting system - Google Patents

Abstract

PURPOSE:To achieve a simpler measuring circuit, a higher accuracy and the like by stopping the time counting in response to changes in the signal value at an input terminal to detect the disconnection position of a transmission line using the time counted. CONSTITUTION:A cable to be detected is connected to a line 5. A step pulse is sent to a cable 10 from a step pulse generation circuit 2. At the same time, a measurement start signal is generated on a line 4 from the circuit 2 makes a time counting circuit 9 start the time counting operation. The step pulse applied to the cable 10 propagates via the cable 10 and a reflection occurs at a point of disconnection caused in the cable. A reflection voltage generated at the disconnection point returns to the input end of the same cable part. The reflection voltage turns to the input end overlapping the step pulse, the voltage at the input end jumps. This voltage transit is detected with a peak voltage detection circuit 7. The time involved is the elapse since the application of the step pulse and a measurement stop signal is generated on the line 8 from the circuit 7 to halt the counting action of the time counting circuit 9.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a disconnection position detection method for detecting a disconnection position of a cable by utilizing reflection at a disconnection point of a cable or the like.

Background of (Iff) Technology In an information processing system, a plurality of input/output devices are connected to the central processing unit via cables.

It is essential for the cable to be able to properly transmit various signals in order to operate the information processing system normally.

However, the cable does not always perform a normal transmission function due to lightning, and sometimes breaks. If this happens, reflection will occur there, making normal transmission of the signal impossible, so it is necessary to prepare a means to deal with such a disconnection.

(C) Prior art and problems When a break in the wire as described above occurs, in order to repair it and restore its transmission function, it is necessary to locate the break point. There are devices that measure impedance. This technique has drawbacks, such as the impedance measurement equipment used for it having a complicated circuit configuration and the difficulty of measuring when the impedance is close to each other.

Purpose of the Invention The present invention was devised in view of the drawbacks of the conventional techniques as described above, and its purpose is to provide a wire breakage location that completely solves the conventional drawbacks by utilizing reflections occurring at the breakage point. The objective is to provide a detection method.

G+,) Structure of the Invention And this object is to measure time at the same time as applying a stepped signal to the input end of the transmission line, stop the time measurement in response to a change in the signal value at the input end, and perform time measurement. This is achieved by detecting the disconnection position of the transmission line using the time.

(F) Embodiments of the Invention The present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the invention. In this figure, ■
2 is a voltage setting circuit that generates a reference voltage, and 2 is a step pulse generation circuit that receives the reference voltage and generates a step pulse on line 3, and also generates a measurement start signal on line 4 at the rising time of the step pulse. . The line 3 is connected to a transmission line (not shown), such as a cable, via a line 5. The line 5 is connected to the peak voltage detection circuit 7 via the X-ray 6, and the circuit 7 also receives the reference voltage of the voltage setting circuit 1, which is generated by superimposing the reflected wave voltage on the step pulse. This is a circuit that generates the rise of the composite voltage generated by the 9 is a time measurement circuit.

Next, the operation of the circuit configured as described above will be explained.

First, a cable whose disconnection point is to be detected is connected to the line 5.

Then, from the step pulse generation circuit 2, (2-
1), the step pulse is connected to the cable 10
sent upwards. At the same time, the circuit 2 generates a measurement start signal on the line 4, causing the time measurement circuit 9 to start the time measurement operation.

The step pulse applied to cable 10 is
0, and reflection occurs at the disconnection point in the cable. Since the reflection coefficient at the disconnection point is +1 due to its nature, the reflected voltage there is equal to the amplitude value E of the step pulse, assuming that there is no loss in the cable. It is assumed that it takes time τ for the step pulse to propagate from the input end of the cable to the disconnection point. Also, let the distance be l.

The reflected voltage generated at the disconnection point returns to the input end through the same cable section (see (2-1) in Figure 2).

Since this reflected voltage is superimposed on the step pulse, when the reflected voltage returns to the input terminal, the voltage at the input terminal jumps to 2E. This voltage transition is detected by the peak voltage detection circuit 7. As is clear from the above, this time is the time when 2τ has elapsed since the application of the Ste-knob pulse (see (2-2) in Figure 2). A stop signal is generated to stop the time measuring operation of the time measuring circuit 9. The time indicated by the circuit 9 is 2τ.

The propagation velocity of the cable is known in advance, and if it is assumed to be ■, the above β can be obtained as l −■ τ.

Note that the reference voltage of the voltage setting circuit is used to determine the output voltage from the steering knob pulse generation circuit 2 according to the type of cable, and is used to set the reference voltage of the peak voltage detection circuit 7 in advance. It is.

(Act) Effects of the Invention As described above, according to the present invention, since the reflection at one location on the WT 1j is utilized for measurement, it is possible to simplify the measurement circuit, improve measurement accuracy, etc. Effects such as providing advantages in measurement can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a waveform diagram of a ++lj signal used to explain the embodiment of the present invention. In the figure, numeral 1 is a voltage setting circuit, 2 is a step/nop pulse generation circuit, 7 is a peak voltage detection circuit, and 9 is a time measurement circuit.

Claims (1)

[Claims] A stepwise signal is applied to the input end of the transmission line and time is measured at the same time, the time measurement is stopped in response to a change in the signal value at the input end, and the measured time is used to determine the disconnection position of the transmission line. A method for detecting the position of a disconnection.